1. Field of the Invention
The present invention relates to internet telephony, and more particularly to a phone that functions both as an ISDN (Integrated Service Digital Network) phone and an IP phone.
2. Discussion of the Related Art
In order to call parties in remote areas, wired phones connected to a PSTN (Public Switched Telephone Network) have traditionally been used. More recently, VoIP (Voice Over Internet Protocol) phones connected to a network such as the Internet (e.g., So-called Internet phones) are being used.
The number of users of Internet services continue to increase and higher data-transmission-rates over the Internet are now required. As a result, applications such as Internet phones, Internet faxes, and Internet broadcastings are in greater demand. In the case of long distance and international calls especially, Internet phones have proven to have an advantage in terms of providing very cost-effective services compared with conventional wired-phones used over PSTN.
However, conventional Internet phone service has at least one drawback. This service is not capable of placing calls without using personal computers having modems. For example, conventional Internet phones are only able to place calls using a deployed network located between PCs (personal computers) having built-in modems in which computer-to-telephone connections exist or between telephones having connections to computer. The dependency of conventional Internet phone service on the use of computer modems places a limitation on where this service may be used, i.e., this service may only be used in areas where computer modems are located. This results in low scalability of network systems.
In order to overcome this drawback and to promote anytime/anywhere phone service at low cost, next-generation Internet phones should be introduced with high data rate capabilities.
Meanwhile, it is noted that ISDN (Integrated Service Digital Network) provides services of voice, non-voice and/or image, etc., through one subscriber line that connects a variety of terminals and equipment. Accordingly, a need exists, which heretofore has not been appreciated, for combining an ISDN phone and a Internet phone into one phone that will enable users to use a variety of services at low cost while at the same time maximizing efficiency of use.